The remote island chain of Hawaii has always been known as a place with a high number of species found nowhere else on the planet.

Indeed, more than 20 percent of the marine life around the main islands is known to be endemic, which is high compared with most places around the world.

But now scientists have discovered a new locale in the Northwestern Hawaiian Islands with a truly astounding level of endemism.

Kure Atoll is the northernmost coral atoll in the world, situated at the other end of the Hawaiian Islands about 1,300 miles northwest of Honolulu.

“To see 100 percent endemism is phenomenal; it’s off the charts,” said Randall Kosaki, with the National Oceanic and Atmospheric Administration. Kosaki is the NOAA Office of National Marine Sanctuaries’ deputy superintendent of Papahanaumokuakea Marine National Monument.

Kosaki is lead author of a study published last month in the scientific journal Marine Biodiversity documenting Kure’s deep coral reef fish communities composed exclusively of unique fishes.

Scientists made the discovery at depths of 300 feet during a research expedition aboard the NOAA’s ship Hi‘ialakai in September. Using high-tech, closed-circuit rebreather dive technology, scientists were able to go much deeper than conventional scuba gear allows.

The coral reefs at depths of 150 to 450 feet are known as “the coral reef twilight zone” and are among the least explored of all marine ecosystems.

Kosaki previously documented extraordinary levels of marine endemism — between 50 and 90 percent — in these deep reefs found amid the three most northern Hawaiian Islands.

But in September his research ship stumbled onto Kure. The researchers had planned to explore other locations, but storms chased them to the northernmost atoll.

From Sept. 15 to 21, the scientists conducted six dives around the atoll, recording all endemic species with no non-Hawaiian species noted.

Interviewed Monday via phone from a research vessel near Pearl and Hermes Reef, Kosaki said the crew had just returned to Kure for four more dives and again recorded endemic creatures only.

“It’s no fluke,” he declared. “This level of endemism is unparalleled.”

The level of endemism appears to grow with the higher latitude, Kosaki said, and he suspects the higher number of endemic species has to do with the colder water. While water temperatures in the main islands are in the high 70s or the low 80s, the deep reefs around Kure registered in the high 50s.

“That’s California water,” he said. “That’s too cold for truly widespread tropical species.”

Kosaki said the reefs at this depth have so little light, it appears as if you are staring at a black-and-white television.

“They don’t call it the twilight zone for nothing,” he said. “But when you flash on a light, it explodes with color.”

With such little light, it makes one wonder why the aquatic life here even needs to have color. Kosaki said the colorful fish might have evolved from shallower reef fishes.

According to the paper, endemic species are important contributors to global biodiversity, but their restricted geographic ranges make them more vulnerable to extinction.

This fact, it says, reinforces the importance of the protection afforded by large marine protected areas such as Papahanaumokuakea Marine National Monument.

The paper’s co-authors are Richard L. Pyle and Robert K. Whitton of Bishop Museum and Jason C. Leonard, Brian B. Hauk and Daniel Wagner of the national monument.